The Seiko 4N21-1090 is a watch model based on the 4N21 movement.
Parts List
| 200WB9SK01 | crystal - crystal (inorganic) |
| 6M30B5SNW0 | crown - crown |
| 6M30B5NNG1 | crown - crown |
| 0F170BA1S | case back gasket - case back gasket |
| XX000 | band - band |
| 3DA075AAA7S | others - second hand |
| 3DA075AAADG | others - second hand |
| 1BG050L0BDS | others - hour hand |
| 2BG075L0BDS | others - minute hand |
| A120BS | others - push pin (for lb) |
| 4N210440XS13 | others - dial |
| 4N210440XS24 | others - dial |
| 4N210450XG13 | others - dial |
| 4N210450XL13 | others - dial |
| 4N2165 | others - machine code |
| 4N21109076A | others - case |
| 82841595 | others - case ring |
| 4N211090 | others - case back |
| 4N21109080A | others - case |
| 0351155 | others - winding stem |
| DZ0040B01 | others - crown and stem gasket |
| 1BG050L0BDG | others - hour hand |
| 2BG075L0BDG | others - minute hand |
| 3EA075A0BDS | others - second hand |